The hormone progesterone is readily converted to 3alpha-OH-5alpha-pregnan-20-one (3alpha,5alpha-THP) in the brains of males and females. In the brain, 3alpha,5alpha-THP acts like a sedative, decreasing anxiety and reducing seizure activity, by enhancing the function of GABA (gamma-aminobutyric acid), the brain's major inhibitory neurotransmitter. Symptoms of premenstrual syndrome (PMS), such as anxiety and seizure susceptibility, are associated with sharp declines in circulating levels of progesterone and, consequently, of levels of 3alpha,5alpha-THP in the brain. Abrupt discontinuation of use of sedatives such as benzodiazepines and ethanol can also produce PMS-like withdrawal symptoms. Here we report a progesterone-withdrawal paradigm, designed to mimic PMS and post-partum syndrome in a rat model. In this model, withdrawal of progesterone leads to increased seizure susceptibility and insensitivity to benzodiazepine sedatives through an effect on gene transcription. Specifically, this effect was due to reduced levels of 3alpha,5alpha-THP which enhance transcription of the gene encoding the alpha4 subunit of the GABA(A) receptor. We also find that increased susceptibility to seizure after progesferone withdrawal is due to a sixfold decrease in the decay time for GABA currents and consequent decreased inhibitory function. Blockade of the alpha4 gene transcript prevents these withdrawal properties. PMS symptoms may therefore be attributable, in part, to alterations in expression of GABA(A) receptor subunits as a result of progesterone withdrawal.

8-hydroxy-2'-deoxyguanosine (8-OH-dG) was first reported in 1984 as a major form of oxidative DNA damage product by heated sugar, Fenton-type reagents and X-irradiation in vitro. 8-OH-dG has been detected in cellular DNA using an HPLC-ECD method in many laboratories. Analyses of 8-OH-dG in animal organ DNA after the administration of oxygen radical-forming chemicals will be useful for assessments of their carcinogenic risk. Its analysis in human leucocyte DNA and in urine is a new approach to the assessment of an individual's cancer risk due to oxidative stress. The increase of the 8-OH-dG level in the cellular DNA, detected by HPLC-ECD method, was supported by its immunochemical detection and its enhanced repair activity. The validity of the general use of 8-OH-dG as a marker of cellular oxidative stress is discussed.

Inositol phospholipids play multiple roles in cell signalling systems. Two widespread eukaryotic phosphoinositide-based signal transduction mechanisms, phosphoinositidase C-catalysed phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) hydrolysis and 3-OH kinase-catalysed PtdIns(4,5)P2 phosphorylation, make the second messengers inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) sn-1,2-diacylglycerol and PtdIns(3,4,5)P3. In addition, PtdIns(4,5)P2 and PtdIns3P have been implicated in exocytosis and membrane trafficking. We now show that when the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe are hyperosmotically stressed, they rapidly synthesize phosphatidylinositol-3,5-bisphosphate (PtdIns(3,5)P2) by a process that involves activation of a PtdIns3P 5-OH kinase. This PtdIns(3,5)P2 accumulation only occurs in yeasts that have an active vps34-encoded PtdIns 3-OH kinase, showing that this latter kinase makes the PtdIns3P needed for PtdIns(3,5)P2 synthesis and indicating that PtdIns(3,5)P2 may have a role in sorting vesicular proteins. PtdIns(3,5)P2 is also present in mammalian and plant cells: in monkey Cos-7 cells, its labelling is inversely related to the external osmotic pressure. The stimulation of a PtdIns3P 5-OH kinase-catalysed synthesis of PtdIns(3,5)P2, a molecule that might be a new type of phosphoinositide 'second messenger, thus appears to be central to a widespread and previously uncharacterized regulatory pathway.

Many flaviviruses are globally important human pathogens. Their plus-strand RNA genome contains a 5'-cap structure that is methylated at the guanine N-7 and the ribose 2'-OH positions of the first transcribed nucleotide, adenine (m(7)GpppAm). Using West Nile virus (WNV), we demonstrate, for the first time, that the nonstructural protein 5 (NS5) mediates both guanine N-7 and ribose 2'-O methylations and therefore is essential for flavivirus 5'-cap formation. We show that a recombinant full-length and a truncated NS5 protein containing the methyltransferase (MTase) domain methylates GpppA-capped and m(7)GpppA-capped RNAs to m(7)GpppAm-RNA, using S-adenosylmethionine as a methyl donor. Furthermore, methylation of GpppA-capped RNA sequentially yielded m(7)GpppA- and m(7)GpppAm-RNA products, indicating that guanine N-7 precedes ribose 2'-O methylation. Mutagenesis of a K(61)-D(146)-K(182)-E(218) tetrad conserved in other cellular and viral MTases suggests that NS5 requires distinct amino acids for its N-7 and 2'-O MTase activities. The entire K(61)-D(146)-K(182)-E(218) motif is essential for 2'-O MTase activity, whereas N-7 MTase activity requires only D(146). The other three amino acids facilitate, but are not essential for, guanine N-7 methylation. Amino acid substitutions within the K(61)-D(146)-K(182)-E(218) motif in a WNV luciferase-reporting replicon significantly reduced or abolished viral replication in cells. Additionally, the mutant MTase-mediated replication defect could not be trans complemented by a wild-type replicase complex. These findings demonstrate a critical role for the flavivirus MTase in viral reproduction and underscore this domain as a potential target for antiviral therapy.

PKB/Akt is a serine/threonine kinase that contains a pleckstrin-homology (PH) domain and is activated in response to growth-factor treatment of cells by a mechanism involving phosphoinositide 3-OH kinase. PKB/Akt provides a survival signal that protects cells from apoptosis induced by various stresses, perhaps explaining its discovery as a retroviral oncogene and its amplification in many human tumours.

Previous studies have shown that recombinant interferon gamma (IFN-gamma), crude T cell supernatants, or appropriate T-cell lines can cause total inhibition of the growth of M. tuberculosis inside murine peritoneal macrophages. In similar experiments with human monocytes much smaller effects are seen. This could be due to the relative immaturity of these cells. Because dihydroxy vitamin D3 (1,25-(OH)2 D3) can cause phenotypic differentiation of immature leukemic lines into macrophage-like cells, we have explored the possibility that exposure to cholecalciferol metabolites in vitro might increase the ability of monocytes to control proliferation of M. tuberculosis, or cause monocytes to mature into cells able to respond appropriately to IFN-gamma. Incubation of monocytes with three cholecalciferol metabolites induced anti-tuberculosis activity to an extent that correlated with their binding affinities to the intracellular receptor protein for the derivatives. 1,25-(OH)2 D3 also primed monocytes for phorbol myristate acetate-triggered reduction of nitroblue tetrazolium. The effects were additive rather than synergistic with those of IFN-gamma. Monocytes incubated with IFN-gamma developed 25-OH D3 1-hydroxylase activity, detected by conversion of tritiated 25-(OH) D3 to a more polar metabolite which coeluted with 1,25-(OH)2 D3 on straight and reverse-phase HPLC. The latter is a more active form in vivo. These findings help to explain claims for the efficacy of vitamin D in the treatment of some forms of tuberculosis, and also the occasional finding of raised serum calcium, and disturbed vitamin D metabolism in these patients.

The klotho gene encodes a novel type I membrane protein of beta-glycosidase family and is expressed principally in distal tubule cells of the kidney and choroid plexus in the brain. These mutants displayed abnormal calcium and phosphorus homeostasis together with increased serum 1,25-(OH)2D. In kl-/- mice at the age of 3 wk, elevated levels of serum calcium (10.9 +/- 0.31 mg/dl vs. 10.0 +/- 0.048 mg/dl in wild-type mice), phosphorus (14.7 +/- 1.1 mg/dl vs. 9.7 +/- 1.5 mg/dl in wild type) and most notably, 1,25-(OH)2D (403 +/- 99.7 mg/dl vs. 88.0 +/- 34.0 mg/dl in wild type) were observed. Reduction of serum 1,25-(OH)2D concentrations by dietary restriction resulted in alleviation of most of the phenotypes, suggesting that they are downstream events resulting from elevated 1,25-(OH)2D. We searched for the signals that lead to up-regulation of vitamin D activating enzymes. We examined the response of 1alpha-hydroxylase gene expression to calcium regulating hormones, such as PTH, calcitonin, and 1,25-(OH)2D3. These pathways were intact in klotho null mutant mice, suggesting the existence of alternate regulatory circuits. We also found that the administration of 1,25-(OH)2D3 induced the expression of klotho in the kidney. These observations suggest that klotho may participate in a negative regulatory circuit of the vitamin D endocrine system, through the regulation of 1alpha-hydroxylase gene expression.

BACKGROUND

Vitamin D deficiency has been described as being pandemic, but serum 25-hydroxyvitamin D [25(OH)D] distribution data for the European Union are of very variable quality. The NIH-led international Vitamin D Standardization Program (VDSP) has developed protocols for standardizing existing 25(OH)D values from national health/nutrition surveys.

OBJECTIVE

This study applied VDSP protocols to serum 25(OH)D data from representative childhood/teenage and adult/older adult European populations, representing a sizable geographical footprint, to better quantify the prevalence of vitamin D deficiency in Europe.

METHODS

The VDSP protocols were applied in 14 population studies [reanalysis of subsets of serum 25(OH)D in 11 studies and complete analysis of all samples from 3 studies that had not previously measured it] by using certified liquid chromatography-tandem mass spectrometry on biobanked sera. These data were combined with standardized serum 25(OH)D data from 4 previously standardized studies (for a total n= 55,844). Prevalence estimates of vitamin D deficiency [using various serum 25(OH)D thresholds] were generated on the basis of standardized 25(OH)D data.

RESULTS

An overall pooled estimate, irrespective of age group, ethnic mix, and latitude of study populations, showed that 13.0% of the 55,844 European individuals had serum 25(OH)D concentrations <30 nmol/L on average in the year, with 17.7% and 8.3% in those sampled during the extended winter (October-March) and summer (April-November) periods, respectively. According to an alternate suggested definition of vitamin D deficiency (<50 nmol/L), the prevalence was 40.4%. Dark-skinned ethnic subgroups had much higher (3- to 71-fold) prevalence of serum 25(OH)D <30 nmol/L than did white populations.

CONCLUSIONS

Vitamin D deficiency is evident throughout the European population at prevalence rates that are concerning and that require action from a public health perspective. What direction these strategies take will depend on European policy but should aim to ensure vitamin D intakes that are protective against vitamin D deficiency in the majority of the European population.

Dent's disease is an X-linked disorder associated with the urinary loss of low-molecular-weight proteins, phosphate and calcium, which often leads to kidney stones. It is caused by mutations in ClC-5, a renal chloride channel that is expressed in endosomes of the proximal tubule. Here we show that disruption of the mouse clcn5 gene causes proteinuria by strongly reducing apical proximal tubular endocytosis. Both receptor-mediated and fluid-phase endocytosis are affected, and the internalization of the apical transporters NaPi-2 and NHE3 is slowed. At steady state, however, both proteins are redistributed from the plasma membrane to intracellular vesicles. This may be caused by an increased stimulation of luminal parathyroid hormone (PTH) receptors owing to the observed decreased tubular endocytosis of PTH. The rise in luminal PTH concentration should also stimulate the hydroxylation of 25(OH) vitamin D3 to the active hormone. However, this is counteracted by a urinary loss of the precursor 25(OH) vitamin D3. The balance between these opposing effects, both of which are secondary to the defect in proximal tubular endocytosis, probably determines whether there will be hypercalciuria and kidney stones.

BACKGROUND

N-acetylcysteine (NAC) has been in clinical practice for several decades. It has been used as a mucolytic agent and for the treatment of numerous disorders including paracetamol intoxication, doxorubicin cardiotoxicity, ischemia-reperfusion cardiac injury, acute respiratory distress syndrome, bronchitis, chemotherapy-induced toxicity, HIV/AIDS, heavy metal toxicity and psychiatric disorders.

METHODS

The mechanisms underlying the therapeutic and clinical applications of NAC are complex and still unclear. The present review is focused on the chemistry of NAC and its interactions and functions at the organ, tissue and cellular levels in an attempt to bridge the gap between its recognized biological activities and chemistry.

CONCLUSIONS

The antioxidative activity of NAC as of other thiols can be attributed to its fast reactions with OH, NO2, CO3(-) and thiyl radicals as well as to restitution of impaired targets in vital cellular components. NAC reacts relatively slowly with superoxide, hydrogen-peroxide and peroxynitrite, which cast some doubt on the importance of these reactions under physiological conditions. The uniqueness of NAC is most probably due to efficient reduction of disulfide bonds in proteins thus altering their structures and disrupting their ligand bonding, competition with larger reducing molecules in sterically less accessible spaces, and serving as a precursor of cysteine for GSH synthesis.

CONCLUSIONS

The outlined reactions only partially explain the diverse biological effects of NAC, and further studies are required for determining its ability to cross the cell membrane and the blood-brain barrier as well as elucidating its reactions with components of cell signaling pathways.

OBJECTIVE

Higher maternal intake of vitamin D during pregnancy is associated with a lower risk of wheezing in offspring. The relationship between cord-blood levels of 25-hydroxyvitamin D (25[OH]D) and childhood wheezing is unknown. We hypothesized that cord-blood levels would be inversely associated with risk of respiratory infection, wheezing, and asthma.

METHODS

Cord blood from 922 newborns was tested for 25(OH)D. Parents were asked if their child had a history of respiratory infection at 3 months of age or a history of wheezing at 15 months of age and then annually thereafter. Incident asthma was defined as doctor-diagnosed asthma by the time the child was 5 years old and reported inhaler use or wheezing since the age of 4 years.

RESULTS

The median cord-blood level of 25(OH)D was 44 nmol/L (interquartile range: 29-78). Follow-up was 89% at the age of 5 years. Adjusting for the season of birth, 25(OH)D had an inverse association with risk of respiratory infection by 3 months of age (odds ratio: 1.00 [reference] for ≥75 nmol/L, 1.39 for 25-74 nmol/L, and 2.16 [95% confidence interval: 1.35-3.46] for <25 nmol/L). Likewise, cord-blood 25(OH)D levels were inversely associated with risk of wheezing by 15 months, 3 years, and 5 years of age (all P < .05). Additional adjustment for more than 12 potential confounders did not materially change these results. In contrast, we found no association between 25(OH)D levels and incident asthma by the age of 5 years.

CONCLUSIONS

Cord-blood levels of 25(OH)D had inverse associations with risk of respiratory infection and childhood wheezing but no association with incident asthma.

We have shown that 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) down-regulates renin expression. To explore the molecular mechanism, we analyzed the mouse Ren-1c gene promoter by luciferase reporter assays. Deletion analysis revealed two DNA fragments from -2,725 to -2,647 (distal fragment) and from -117 to +6 (proximal fragment) that are sufficient to mediate the repression. Mutation of the cAMP response element (CRE) in the distal fragment blunted forskolin stimulation as well as 1,25(OH)(2)D(3) inhibition of the transcriptional activity, suggesting the involvement of CRE in 1,25(OH)(2)D(3)-induced suppression. EMSA revealed that 1,25(OH)(2)D(3) markedly inhibited nuclear protein binding to the CRE in the promoter. ChIP and GST pull-down assays demonstrated that liganded VDR blocked the binding of CREB to the CRE by directly interacting with CREB with the ligand-binding domain, and the VDR-mediated repression can be rescued by CREB, CBP, or p300 overexpression. These data indicate that 1,25(OH)(2)D(3) suppresses renin gene expression at least in part by blocking the formation of CRE-CREB-CBP complex.

OBJECTIVE

To validate the FRAIL scale.

METHODS

Longitudinal study.

METHODS

Community.

METHODS

Representative sample of African Americans age 49 to 65 years at onset of study.

METHODS

The 5-item FRAIL scale (fatigue, resistance, ambulation, illnesses, and loss of weight), at baseline and activities of daily living (ADLs), instrumental activities of daily living (IADLs), mortality, short physical performance battery (SPPB), gait speed, one-leg stand, grip strength and injurious falls at baseline and 9 years. Blood tests for CRP, SIL6R, STNFR1, STNFR2 and 25 (OH) vitamin D at baseline.

RESULTS

Cross-sectionally the FRAIL scale correlated significantly with IADL difficulties, SPPB, grip strength and one-leg stand among participants with no baseline ADL difficulties (N=703) and those outcomes plus gait speed in those with no baseline ADL dependencies (N=883). TNFR1 was increased in pre-frail and frail subjects and CRP in some subgroups. Longitudinally (N=423 with no baseline ADL difficulties or N=528 with no baseline ADL dependencies), and adjusted for the baseline value for each outcome, being pre-frail at baseline significantly predicted future ADL difficulties, worse one-leg stand scores, and mortality in both groups, plus IADL difficulties in the dependence-excluded group. Being frail at baseline significantly predicted future ADL difficulties, IADL difficulties, and mortality in both groups, plus worse SPPB in the dependence-excluded group.

CONCLUSIONS

This study has validated the FRAIL scale in a late middle-aged African American population. This simple 5-question scale is an excellent screening test for clinicians to identify frail persons at risk of developing disability as well as decline in health functioning and mortality.

T4 RNA ligase was used to construct a deoxypentanucleotide containing a single 8-hydroxyguanine (7-hydro-8-oxoguanine; G8-OH) residue, which is one of the putatively mutagenic DNA adducts produced by oxidants and ionizing radiation. The pentamer d(GCTAG8-OH)p was prepared by the ligation of a chemically synthesized acceptor molecule, d(GCTA), to an adducted donor, 8-hydroxy-2'-deoxyguanosine 5',3'-bisphosphate. The acceptor was efficiently converted to the reaction product (greater than 95%), and the final product yield was 50%. Following 3'-dephosphorylation, the pentamer was characterized by UV spectroscopy, by high-pressure liquid chromatography, and by gas chromatography-mass spectrometry of the nucleosides released by enzymatic hydrolysis. Both d(GCTAG8-OH) and an unmodified control were 5'-phosphorylated by using [gamma -32P]ATP and incorporated covalently by DNA ligase into a five-base gap at a unique NheI restriction site in the otherwise duplex genome of an M13mp19 derivative. The ligation product contained G8-OH at the 3' residue of an in-frame amber codon (5'-TAG-3') (genome position 6276) of the phage lacZ alpha gene. The adduct was part of a nonsense codon in a unique restriction site in order to facilitate the identification and selection of mutants generated by the replication of the modified genome in Escherichia coli. Both control and adducted pentamers ligated into the genome at 50% of the maximum theoretical efficiency, and nearly all (approximately 90%) of the site-specifically adducted products possessed pentanucleotides that were covalently linked at both 5' and 3' termini. The G8-OH lesion in the NheI site inhibited the cleavage of the site by a 200-fold excess of NheI.(ABSTRACT TRUNCATED AT 250 WORDS)

In all species tested, except humans, biological differences between vitamins D2 and D3 are accepted as fact. To test the presumption of equivalence in humans, we compared the ability of equal molar quantities of vitamin D2 or D3 to increase serum 25-hydroxyvitamin D [25(OH)D], the measure of vitamin D nutrition. Subjects took 260 nmol (approximately 4000 IU) vitamin D2 (n=17) or vitamin D3 (n=55) daily for 14 d. 25(OH)D was assayed with a method that detects both the vitamin D2 and D3 forms. With vitamin D3, mean (+/-SD) serum 25(OH)D increased from 41.3+/-17.7 nmol/L before to 64.6+/-17.2 nmol/L after treatment. With vitamin D2, the 25(OH)D concentration went from 43.7+/-17.7 nmol/L before to 57.4+/-13.0 nmol/L after. The increase in 25(OH)D with vitamin D3 was 23.3+/-15.7 nmol/L, or 1.7 times the increase obtained with vitamin D2 (13.7+/-11.4 nmol/L; P=0.03). There was an inverse relation between the increase in 25(OH)D and the initial 25(OH)D concentration. The lowest 2 tertiles for basal 25(OH)D showed larger increases in 25(OH)D: 30.6 and 25.5 nmol/L, respectively, for the first and second tertiles. In the highest tertile [25(OH)D >49 nmol/L] the mean increase in 25(OH)D was 13.3 nmol/L (P < 0.03 for comparison with each lower tertile). Although the 1.7-times greater efficacy for vitamin D3 shown here may seem small, it is more than what others have shown for 25(OH)D increases when comparing 2-fold differences in vitamin D3 dose. The assumption that vitamins D2 and D3 have equal nutritional value is probably wrong and should be reconsidered.

BACKGROUND

Vitamin D has been shown to influence cardiac contractility and myocardial calcium homeostasis.

OBJECTIVE

We aimed to elucidate whether insufficient vitamin D status is associated with heart failure and sudden cardiac death (SCD).

METHODS

We measured 25-hydroxyvitamin D [25(OH)D] levels in 3299 Caucasian patients who were routinely referred to coronary angiography at baseline (1997-2000).

METHODS

The main outcome was cross-sectional associations of 25(OH)D levels with measures of heart failure and Cox proportional hazard ratios for deaths due to heart failure and for SCD according to vitamin D status.

RESULTS

25(OH)D was negatively correlated with N-terminal pro-B-type natriuretic peptide and was inversely associated with higher New York Heart Association classes and impaired left ventricular function. During a median follow-up time of 7.7 yr, 116 patients died due to heart failure and 188 due to SCD. After adjustment for cardiovascular risk factors, the hazard ratios (with 95% confidence intervals) for death due to heart failure and for SCD were 2.84 (1.20-6.74) and 5.05 (2.13-11.97), respectively, when comparing patients with severe vitamin D deficiency [25(OH)D <25 nmol/liter)] with persons in the optimal range [25(OH)D>> or =75 nmol/liter]. In all statistical analyses, we obtained similar results with 25(OH)D and with 1,25-dihydroxyvitamin D.

CONCLUSIONS

Low levels of 25(OH)D and 1,25-dihydroxyvitamin D are associated with prevalent myocardial dysfunction, deaths due to heart failure, and SCD. Interventional trials are warranted to elucidate whether vitamin D supplementation is useful for treatment and/or prevention of myocardial diseases.

Toll-like receptors (TLR) represent an ancient front-line defence system that enables the host organism to sense the presence of microbial components within minutes. As inducers of inflammation, TLR act as important triggers of distinct entities such as sepsis or autoimmune disease exacerbation. We report here that vitamin D3 [1alpha,25-dihydroxycholecalciferol, 1,25(OH)(2)D3] suppresses the expression of TLR2 and TLR4 protein and mRNA in human monocytes in a time- and dose-dependent fashion. Despite 1,25(OH)(2)D3-induced up-regulation of CD14, challenge of human monocytes with either LPS or lipoteichoic acid resulted in impaired TNF-alpha and procoagulatory tissue factor (CD142) production, emphasizing the critical role of TLR in the induction of inflammation. Moreover, reduced TLR levels in 1,25(OH)(2)D3-treated phagocytes were accompanied by impaired NF-kappaB/RelA translocation to the nucleus and by reduced p38 and p42/44 (extracellular signal-regulated kinase 1/2) phosphorylation upon TLR-ligand engagement. Both TLR down-regulation and CD14 up-regulation were substantially inhibited by the vitamin D receptor (VDR) antagonist ZK 159222, indicating that the immunomodulatory effect of 1,25(OH)(2)D3 on innate immunity receptors requires VDR transcription factor activation. Our data provide strong evidence that 1,25(OH)(2)D3 primes monocytes to respond less effectively to bacterial cell wall components in a VDR-dependent mechanism, most likely due to decreased levels of TLR2 and TLR4.

The elevated "zero-maze" is a modification of the elevated plus-maze model of anxiety in rats which incorporates both traditional and novel ethological measures in the analysis of drug effects. The novel design comprises an elevated annular platform with two opposite enclosed quadrants and two open, removing any ambiguity in interpretation of time spent on the central square of the traditional design and allowing uninterrupted exploration. Using this model, the reference benzodiazepine anxiolytics, diazepam (0.125-0.5 mg/kg) and chlordiazepoxide (0.5-2.0 mg/kg) significantly increased the percentage of time spent in the open quadrants (% TO) and the frequency of head dips over the edge of the platform (HDIPS), and reduced the frequency of stretched attend postures (SAP) from the closed to open quadrants. In contrast, the anxiogenic drug m-chlorophenyl-piperazine (mCPP; 0.25-1.0 mg/kg) induced the opposite effects, decreasing %TO and HDIPS, and increasing SAP. The 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.001-0.1 mg/kg) had no effects on either %TO or HDIPS, but did decrease SAP at 0.01 mg/kg although not at higher or lower doses. Similarly, the 5-HT3 receptor antagonist, ondansetron (0.0001-1.0 mg/kg) decreased SAP and increased %TO at 0.01 mg/kg, but not at other doses. The present data suggest that a combination of the novel "zero-maze" design and a detailed ethological analysis provides a sensitive model for the detection of anxiolytic/anxiogenic drug action.

Arsenic (As) is a toxic metalloid element that is present in air, water and soil. Inorganic arsenic tends to be more toxic than organic arsenic. Examples of methylated organic arsenicals include monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)]. Reactive oxygen species (ROS)-mediated oxidative damage is a common denominator in arsenic pathogenesis. In addition, arsenic induces morphological changes in the integrity of mitochondria. Cascade mechanisms of free radical formation derived from the superoxide radical, combined with glutathione-depleting agents, increase the sensitivity of cells to arsenic toxicity. When both humans and animals are exposed to arsenic, they experience an increased formation of ROS/RNS, including peroxyl radicals (ROO•), the superoxide radical, singlet oxygen, hydroxyl radical (OH•) via the Fenton reaction, hydrogen peroxide, the dimethylarsenic radical, the dimethylarsenic peroxyl radical and/or oxidant-induced DNA damage. Arsenic induces the formation of oxidized lipids which in turn generate several bioactive molecules (ROS, peroxides and isoprostanes), of which aldehydes [malondialdehyde (MDA) and 4-hydroxy-nonenal (HNE)] are the major end products. This review discusses aspects of chronic and acute exposures of arsenic in the etiology of cancer, cardiovascular disease (hypertension and atherosclerosis), neurological disorders, gastrointestinal disturbances, liver disease and renal disease, reproductive health effects, dermal changes and other health disorders. The role of antioxidant defence systems against arsenic toxicity is also discussed. Consideration is given to the role of vitamin C (ascorbic acid), vitamin E (α-tocopherol), curcumin, glutathione and antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase in their protective roles against arsenic-induced oxidative stress.

Within the last 7 years, HLA and disease studies have made it clear that most of the diseases previously known to be HLA-A- or B-associated do in fact show stronger associations with HLA-D/DR antigens. This observation strengthens the assumption that Ir and/or Is determinants are responsible for these associations in agreement with the fact that many of these diseases are characterized by autoimmune phenomena. However, some diseases, ankylosing spondylitis in particular, still show stronger associations with HLA-ABC than with DR antigens. Among the conditions which have been shown to be HLA-associated more recently, four deserves special mention: (i) maternal immunization against the Zwa antigen because this is a good candidate for an antigen-specific Ir gene action; (ii) IgA deficiency in blood donors because this is a non-antigen-specific immunodeficiency; (iii) idiopathic hemochromatosis and (iv) congenital adrenal hyperplasia due to 21-OH deficiency because immune mechanisms are unlikely to be involved. HLA studies and new genetic methodology have significantly advanced our knowledge about the inheritance of some diseases. Thus, HLA-B27 or a B27-associated HLA factor confers a dominant susceptibility to ankylosing spondylitis. HLA plays a definite and strong role in the susceptibility to IDDM, but simple genetic models (dominant, recessive, and intermediate) have been made unlikely on the basis of HLA results; the hypothesis that there are two different susceptibility genes within the HLA system still remains viable, but the demonstration of clinical heterogeneity and/or (better) of different pathogenetic pathways for DR3- and DR4-associated IDDM is required to substantiate it.

Glaucoma is a widespread ocular disease characterized by a progressive loss of retinal ganglion cells (RGCs). Previous studies suggest that the cytokine tumor necrosis factor-alpha (TNF-alpha) may contribute to the disease process, although its role in vivo and its mechanism of action are unclear. To investigate pathophysiological mechanisms in glaucoma, we induced ocular hypertension (OH) in mice by angle closure via laser irradiation. This treatment resulted in a rapid upregulation of TNF-alpha, followed sequentially by microglial activation, loss of optic nerve oligodendrocytes, and delayed loss of RGCs. Intravitreal TNF-alpha injections in normal mice mimicked these effects. Conversely, an anti-TNF-alpha-neutralizing antibody or deleting the genes encoding TNF-alpha or its receptor, TNFR2, blocked the deleterious effects of OH. Deleting the CD11b/CD18 gene prevented microglial activation and also blocked the pathophysiological effects of OH. Thus TNF-alpha provides an essential, although indirect, link between OH and RGC loss in vivo. Blocking TNF-alpha signaling or inflammation, therefore, may be helpful in treating glaucoma.

DNA double-strand breaks originating from diverse causes in eukaryotic cells are accompanied by the formation of phosphorylated H2AX (gammaH2AX) foci. Here we show that gammaH2AX formation is also a cellular response to topoisomerase I cleavage complexes known to induce DNA double-strand breaks during replication. In HCT116 human carcinoma cells exposed to the topoisomerase I inhibitor camptothecin, the resulting gammaH2AX formation can be prevented with the phosphatidylinositol 3-OH kinase-related kinase inhibitor wortmannin; however, in contrast to ionizing radiation, only camptothecin-induced gammaH2AX formation can be prevented with the DNA replication inhibitor aphidicolin and enhanced with the checkpoint abrogator 7-hydroxystaurosporine. This gammaH2AX formation is suppressed in ATR (ataxia telangiectasia and Rad3-related) deficient cells and markedly decreased in DNA-dependent protein kinase-deficient cells but is not abrogated in ataxia telangiectasia cells, indicating that ATR and DNA-dependent protein kinase are the kinases primarily involved in gammaH2AX formation at the sites of replication-mediated DNA double-strand breaks. Mre11- and Nbs1-deficient cells are still able to form gammaH2AX. However, H2AX-/- mouse embryonic fibroblasts exposed to camptothecin fail to form Mre11, Rad50, and Nbs1 foci and are hypersensitive to camptothecin. These results demonstrate a conserved gammaH2AX response for double-strand breaks induced by replication fork collision. gammaH2AX foci are required for recruiting repair and checkpoint protein complexes to the replication break sites.

The molecular details of the nucleotidyl transferase reaction have remained speculative, as strategies to trap catalytic intermediates for structure determination utilize substrates lacking the primer terminus 3'-OH and catalytic Mg2+, resulting in an incomplete and distorted active site geometry. Since the geometric arrangement of these essential atoms will impact chemistry, structural insight into fidelity strategies has been hampered. Here, we present a crystal structure of a precatalytic complex of a DNA polymerase with bound substrates that include the primer 3'-OH and catalytic Mg2+. This catalytic intermediate was trapped with a nonhydrolyzable deoxynucleotide analog. Comparison with two new structures of DNA polymerase beta lacking the 3'-OH or catalytic Mg2+ is described. These structures provide direct evidence that both atoms are required to achieve a proper geometry necessary for an in-line nucleophilic attack of O3' on the alphaP of the incoming nucleotide.

OBJECTIVE

Because vitamin D deficiency is associated with a variety of chronic diseases, understanding the characteristics that promote vitamin D deficiency in otherwise healthy adults could have important clinical implications. Few studies relating vitamin D deficiency to obesity have included direct measures of adiposity. Furthermore, the degree to which vitamin D is associated with metabolic traits after adjusting for adiposity measures is unclear.

METHODS

We investigated the relations of serum 25-hydroxyvitamin D (25[OH]D) concentrations with indexes of cardiometabolic risk in 3,890 nondiabetic individuals; 1,882 had subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volumes measured by multidetector computed tomography (CT).

RESULTS

In multivariable-adjusted regression models, 25(OH)D was inversely associated with winter season, waist circumference, and serum insulin (P < 0.005 for all). In models further adjusted for CT measures, 25(OH)D was inversely related to SAT (-1.1 ng/ml per SD increment in SAT, P = 0.016) and VAT (-2.3 ng/ml per SD, P < 0.0001). The association of 25(OH)D with insulin resistance measures became nonsignificant after adjustment for VAT. Higher adiposity volumes were correlated with lower 25(OH)D across different categories of BMI, including in lean individuals (BMI <25 kg/m(2)). The prevalence of vitamin D deficiency (25[OH]D <20 ng/ml) was threefold higher in those with high SAT and high VAT than in those with low SAT and low VAT (P < 0.0001).

CONCLUSIONS

Vitamin D status is strongly associated with variation in subcutaneous and especially visceral adiposity. The mechanisms by which adiposity promotes vitamin D deficiency warrant further study.